Claude Sonnet 5.5 is now available on Tchavi

Claude Sonnet 5.5 is available on Tchavi today, under the ID claude-sonnet-5-5. If you already use Claude Sonnet 5, you can test it by changing one line. One thing to check first: if your code forces a specific tool call, read the section on tools below.

In short

• Tchavi, an OpenAI-compatible AI API gateway you pay for with mobile money, adds Claude Sonnet 5.5: claude-sonnet-5-5.
• 1M-token context, output up to 128K tokens, image and PDF input, tool calling, streaming.
• Forced tool calls (tool_choice set to any or tool) are rejected by Anthropic on this model. auto works.
• Prices are on the model page.

What is new

Claude Sonnet 5.5 is the most recent model in Anthropic's Sonnet family. On Tchavi it has its own line in the catalogue: it does not replace Claude Sonnet 5, which stays available under its own ID. You choose when to move from one to the other.

What it is for

Sonnet 5.5 is a general-purpose model built for long work:

• Large documents. A 200-page contract, a codebase or a quarter of support tickets fit in a single request thanks to the 1M-token window.
• Long outputs. Up to 128K tokens in one pass: a full report or a migration diff.
• Vision and documents. It reads images and PDFs in the same request as your text.
• Adaptive thinking. It decides how long to think and stays fast on easy turns.

These capabilities come from Anthropic's documentation, copied into our verified model sheet.

What to know before you integrate it

Three behaviours matter if you are migrating existing code. I checked the first one directly against the API on the day the model was added.

Forced tool calls are rejected. Anthropic removed tool_choice: any and tool_choice: tool on this model: a request that forces a specific tool returns a 400 error. Tchavi does not emulate forced calls, so the request fails. If your integration depends on it, stay on Claude Sonnet 5.

Sampling parameters are ignored. Anthropic removed temperature, top_p and top_k on this model. Tchavi drops them from the request rather than letting it fail.

Third point, noted in the model sheet: text written between two tool calls arrives in thinking blocks, not as plain content. If your interface only shows streamed text, it can look idle while an agent is working.

One call to try it

Same format as the OpenAI API, with Tchavi's base URL:

curl https://tchavi.com/api/v1/chat/completions \
  -H "Authorization: Bearer $TCHAVI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "messages": [
      {"role": "user", "content": "Summarise this contract in five points, and list the clauses that allow a price increase."}
    ],
    "max_tokens": 1024
  }'

The cost of each call is in the X-Credits-Used response header. For Claude Code and Anthropic-format clients, the base URL is https://tchavi.com/api.

How to try it

1. Open the model page: prices, capabilities and limits, as billed.
2. Create an API key, then follow the quickstart or the chat completions page.
3. Top up with mobile money from KES 250 (M-Pesa in Kenya, MTN or Airtel elsewhere; see countries and operators). Credits you buy do not expire.

FAQ

Should I migrate from Claude Sonnet 5?

Not necessarily. Both stay available. Test Sonnet 5.5 on your own prompts and keep Sonnet 5 if you force tool calls.

Are the prices on this page?

No. Prices change, and the model page always shows the price billed today.

Can I use it with the OpenAI SDK?

Yes. Set the base URL to https://tchavi.com/api/v1, use your Tchavi key and pass claude-sonnet-5-5 as the model.

create your account and top up KES 250

This article is part of the series "Building an AI product from Africa". Tchavi is an OpenAI-compatible AI API gateway: one key gives access to over 100 text, image, audio and video models, and you pay for it with mobile money, no bank card (countries and operators). More guides on the blog. Follow us: LinkedIn and X.